Manufacture of sulfid of zinc.



JOSEPH KOETSCHET AND JOANNES CLATJ'DE ANTOINE MEYER, 0F LYON, FRANCE;SAID IlZOETSCHET ASSIGNOR, BY MESNE ASSIGNMENTS, T0 SAID MEYER.

MANUFACTURE OF SULFID OF ZINC.

No Drawing.

a citizen of the Swiss Confederation, residing at St. Fons, Lyon, 'inthe Republic of France, scientific director of Societe Chimique desUsines du Rhone, and JoANNEs CLAUDE ANTOINE MEYER, a citizen of theRepublic of'l rance, residing at 208 Avenue Felix Faure, Lyon, France,chemist, have invented a new and Improved Manufacture of Sulfidof Zinc,of which the following is a. specification.

Among the substances capable of serving as substitutes for white lead,those which have hitherto found most favor are zinc oxid and lithopone.Zinc oxid or zinc white is obtained by distilling metallic zinc, butapart from its dearness it possesses the disadvantages that it has aninsuflicient covering power and that it cannot be used for outside workowing to its inability to stand the weather. As regards lithopone, whichis composed of about 30 per cent. of sulfid of zinc and 7 0 per cent. ofbarium sulfate, this has a considerably greater covering power than oxidof zinc, but on the other hand it is subject to the objections ofblackening in the light and of containing too great a proportion ofbarium sulfate, which possesses almost no covering power at all. Itfollows that the covering power of the mixture known as lithopone isalmost entirely due to the presence of the zinc sulfid. Further it hasbeen long recognized that pure sulfid of zinc has a much greatercovering power than white lead, but the difliculty of obtain ing itperfectly white-and relatively cheaply has not hitherto allowed of itsbeing used for painting. It is known that it is possible to precipitatesmall quantities of sulfid of zinc from zinc vsalts of mineral acids bymeansof sulfureted hydrogen, but the pre-- cipitation is arrestedveryrapidly when the operation is performed under the usual conditions.This stopping of the reactions has hitherto been attributed to theincrease of free acid formed in the solution and consequently care isalways taken in practice to work with very dilute solutions with theobject of obtaining sufficient precipitation.

We have found that contrary to the views above indicated it is possibleto precipitate from an almost saturated solution of sulfateSpecification of Letters Patent. Patented rune 3, 1913. Applicationfiled December 1, 1908. Serial No. 465,542.

of zinc (for example) the greater portion of the zinc in the formof asu-lfid by establishing intimate and prolonged contact between thesolution and the sulfur eted hydrogen.

Example: A solution containing 45 per cent. of crystallized zinc sulfateis s rayed or atomized in an atmosphere of sulfureted hydrogen and thecontact is maintained until the gas ceases to be absorbed. The greaterportion of the zinc is thus converted into a pulverulent sulfid whichcan be easily filtered, as it presents no obstruction to the passage ofthe liquid durin the filtration. This product is separated rom theliquid portion which is strongly acid and can serve again forregenerating the initial solution by neutralization with a suitable zincore and purification by the known means. The idea underlying theinvention consists in the intimate mixture of the liquid and gas, and itwill be understood that this mixture can be attained by any knownarrangement allowing of reducing aliquid to a state of division or ofsimply increasing the surface exposed. It issometimes convenient totreat first with a; weak current of H S which frees the solution fromthe heavy metals such as copper, tin, bismuth, cadmium, and antimony,which may be present as impurities. The solution is then filtered and isready for the precipitation of the sulfid of zinc. The solutionseparated from the zinc sulfid can serve again for obtaining a new crudesolution of zinc sulfate which serves as raw material. The sulfid ofzinc obtained, which is chemically pure, is dried and can be used forpainting work. It has a covering power 1.6 times greater than that ofwhite lead.

The product manufactured according to this invention is distinguishedfrom zinc sulfids precipitated according to the usual process by itsnon-colloidal pulverulent structure and its property of resisting theaction of dilute mineral acids.

\Vhat we claim and desire to secure by Letters Patent is 1. A processfor the manufacture of sulfid of zinc comprising subjection of aconcentrated solution of zinc salts of mineral acids to intimate andprolonged contact with sulfureted hydrogen.

2. A process for the manufacture of sulfid of zinc comprising subjectionof a concentrated solution of sulfate of zinc to intimate and prolongedcontact with sulfureted hydrogen.

3. A process for the manufacture of sulfid of zinc, comprisingsubjection of a solution of crude zinc sulfate to preliminary treatmentwith sulfureted hydrogen with the object of precipitating impurities,filtration of the liquid, and subjection of the same as a concentratedsolution to intimate and prolonged contact with sulfureted hydrogen toprecipitate zinc sulfid.

4. A process for the. manufacture of sulfid of zinc, comprisingsubjection of a concentrated solution of crude zinc sulfate to intimateand prolonged contact with sulfureted hydrogen until the solutionattains strong acidity.

5. A process for the manufacture of sulfid of zinc comprising thesubjection of a concentrated solution of zinc salts of mineral acidscontaining a greater proportion than one per cent. of metallic zinc toint-imate and prolonged contact with sulfureted hydrogen.

6. A process for the manufacture of sulfid of zinc comprising thesubjection of a concentrated solution of sulfate of zinc, said solutioncontaining a greater proportion than one per cent. of metallic zinc tointimate and prolonged contact with sulfureted hydrogen.

7. A process for the manufactureof sulfid of Zinc which comprises thesubjection of .a concentrated solution of zinc salts of mineral acids tointimate and'prolonged contact with sulfureted hydrogen at ordinarytemperatures without the application of heat.

8. A process for the manufacture of sulfid of zinc comprising thesubjection of a concentrated solution of sulfate of zinc to sub-dividedconcentrated solutionof zinc salts of mineral acids to sulfuretedhydrogen.

11. A process for the manufacture of sulfid of zinc comprising thesubjection of a sub-divided concentrated solution of sulfate of zinc tosulfureted hydrogen.

12. A process for the manufacture of sulfid of zinc comprising thesubjection of a sub-divided concentrated solution of crude zinc sulfateto sulfureted hydrogen until the solution attains a strong acidity.

13. A process for the' manufacture of sulfid of zinc comprising theatomizing of a concentrated solution containing approximately forty-fiveper cent. of crystallized zinc sulfate in an atmosphere of sulfuretedhydrogen and maintaining contact until the gas ceases to be absorbed.

In witness whereof, we have hereunto signed our names in the presence oftwo subscribing .Witnesses.

JOSEPH KOETSCHET. JOANNES CLAUDE ANTOINE MEYER.

VVit-nesses:

'IHos. N. BROWNE, MARIN VACHON.

